title: Influence of antipseudomonal agents on Pseudomonas aeruginosa colonization and acquisition of resistance in critically ill medical patients.
abstract: OBJECTIVE
  To assess the role of antipseudomonal agents on Pseudomonas aeruginosa colonization and acquisition of resistance.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Two medical intensive care units.
  
  
  METHODS
  346 patients admitted for >or= 48 h.
  
  
  METHODS
  Analysis of data from an 8-month study comparing a mixing versus a cycling strategy of antibiotic use.
  
  
  RESULTS
  Surveillance cultures from nares, pharynx, rectum, and respiratory secretions were obtained thrice weekly. Acquisition of resistance was defined as the isolation, after 48 h of ICU stay, of an isolate resistant to a given antibiotic if culture of admission samples were either negative or positive for a susceptible isolate. Emergence of resistance refers to the conversion of a defined pulsotype from susceptible to non-susceptible. Forty-four (13%) patients acquired 52 strains of P. aeruginosa. Administration of piperacillin-tazobactam for >or= 3 days (OR 2.6, 95% CI 1.09-6.27) and use of amikacin for >or= 3 days (OR 2.6, 95% CI 1.04-6.7) were positively associated with acquisition of P. aeruginosa, whereas use of quinolones (OR 0.27, 95% CI 0.1-0.7) and antipseudomonal cephalosporins (OR 0.27, 95% CI 0.08-0.9) was protective. Exposure to quinolones and cephalosporins was not associated with the acquisition of resistance, whereas it was linked with usage of all other agents. Neither quinolones nor cephalosporins were a major determinant on the emergence of resistance to themselves, as resistance to these antibiotics developed at a similar frequency in non-exposed patients.
  
  
  CONCLUSIONS
  In critically ill patients, quinolones and antipseudomonal cephalosporins may prevent the acquisition of P. aeruginosa and may have a negligible influence on the acquisition and emergence of resistance.
authors.affiliation: Department of Infectious Diseases, Hospital Clínic, IDIBAPS, University of Barcelona, Barcelona, Spain. jamarti@clinic.ub.es
authors.forename: José A
authors.initials: JA
authors.lastname: Martínez
authors.forename: Esther
authors.initials: E
authors.lastname: Delgado
authors.forename: Sara
authors.initials: S
authors.lastname: Martí
authors.forename: Francesc
authors.initials: F
authors.lastname: Marco
authors.forename: Jordi
authors.initials: J
authors.lastname: Vila
authors.forename: Josep
authors.initials: J
authors.lastname: Mensa
authors.forename: Antoni
authors.initials: A
authors.lastname: Torres
authors.forename: Carles
authors.initials: C
authors.lastname: Codina
authors.forename: Antoni
authors.initials: A
authors.lastname: Trilla
authors.forename: Alex
authors.initials: A
authors.lastname: Soriano
authors.forename: Aitor
authors.initials: A
authors.lastname: Alquezar
authors.forename: Pedro
authors.initials: P
authors.lastname: Castro
authors.forename: José M
authors.initials: JM
authors.lastname: Nicolás
mesh_terms: D000328:Adult; D002511:Cephalosporins / Q000627:therapeutic use*; D016638:Critical Illness / Q000453:epidemiology*; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D004338:Drug Combinations; D004352:Drug Resistance, Microbial; D004359:Drug Therapy, Combination; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D005814:Genes, Viral / Q000235:genetics; D005838:Genotype; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D008297:Male; D010614:Pharynx / Q000382:microbiology; D010878:Piperacillin / Q000627:therapeutic use*; D011446:Prospective Studies; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000302:isolation & purification*; D015363:Quinolones / Q000627:therapeutic use*; D012007:Rectum / Q000382:microbiology; D020545:Respiratory Mucosa / Q000382:microbiology
chemical_list: D002511:Cephalosporins; D004338:Drug Combinations; D004791:Enzyme Inhibitors; D015363:Quinolones; D010878:Piperacillin